Agreed but it's not that black and white. The overall success of the decriminalization also depends on the culture and education level of the populace and the ability of the govt to enforce the laws. From, what i remember of my talk with ngo friends in india, in a poor developing country like india or bangladesh, legalization of prostitution would actually increase the trafficking.
Similar reason why allowing everyone firearms works in Scandinavian countries but is an issue in the US